The present invention relates to a tubular food casing, and further to a process for the manufacture and its use as an artificial sausage casing.
Tubular food casings based on cellulose hydrate, which have an untreated inside surface, find only limited use as sausage casings since, in the case of fresh sausages, the sausage meat adheres so firmly to the packaging casing that the casing can hardly be peeled from the filling when required and, in the case of uncooked sausages, for example, dry sausages, adhesion is so poor that the casing detaches itself from the sausage meat in the drying process during storage. As a consequence of this separation of the casing from the filling in the course of drying of the long-keeping sausage, the casing does not shrink together with the filling and thus becomes wrinkled and unsightly.
U.S. Pat. No. 3,935,320 discloses artificial sausage casings based on cellulose hydrate, for use in the production of dry sausages. These casings are provided on their inside and outside surfaces with coatings of proteinaceous chemical compounds in order to obtain sufficient adhesion between the sausage meat and the casing. Proteinaceous compounds of the type mentioned include, for example, a chemically modified protein, such as casein or gelatin (U.S. Pat. No. 4,142,013) and epichlorohydrin-polyamine-polyamide, urea-formaldehyde or melamine-formaldehyde resins (U.S. Pat. No. 3,378,379).
However, reaction between these substances and the hydroxyl groups of the cellulose does not sufficiently terminate before the casing exits the drying device. There is, therefore, a risk that the substances will partially react with the hydroxyl groups of the adjoining opposite surface of the tubular casing after the casing has been laid flat and rolled up, especially if the tubing has a high moisture content and is subjected to strong compression. This reaction becomes apparent as an undesired adhesion of the tubular casing when it is used for further processing, for example, shirring or stuffing, after having been stored on a roll.
Furthermore, the use of the afore-mentioned chemical compounds frequently involves the risk that the cellulose hydrate forming the tubular casing will cross-link in an undesirable and uncontrollable manner, rendering the casing brittle. When the tubular casing is then used for its intended purpose, for example, when it is shirred, breaks or holes may appear in the tubing wall.
It is also a disadvantage that for each type of casing the amount of coating substance applied must lie within a specific, relatively narrow range. If this range is exceeded, difficulties with peeling of the casing will occur; on the other hand, if the amount falls below this range, the tubular casing will separate from the filling.